Hydrocarbylamine additives for distillate fuels

ABSTRACT

A mixture of high and low molecular weight hydrocarbyl amines exhibit excellent detergency and dispersancy at low concentrations in fuels. The high molecular weight hydrocarbyl amine contains at least one hydrocarbyl group having a molecular weight from about 1,900 to 5,000 and the low molecular weight hydrocarbyl amine contains at least one hydrocarbyl group having a molecular weight from about 300 to 600. The weight ratio of low molecular weight amine to high molecular weight amine in the mixture is maintained between about 0.5 and 5:1.

United States Patent Honnen Aug. 5, 1975 HYDROCARBYLAMINE ADDITIVES FORDISTILLATE FUELS Inventor: Lewis R. l-lonnen, Petaluma, Calif.

Assignee: Chevron Research Company, San

Francisco, Calif.

Filed: Oct. 11, 1973 Appl. No.: 405,707

Related U.S. Application Data Continuation-impart of Ser. Nos. 318,064,Dec. 26, 1972, abandoned, and Ser. No. 318,063, Dec. 26, I972,abandoned.

U.S. Cl. 44/58; 44/63; 44/74;

44/72 Int. Cl Cl0l 1/22 Field of Search 44/74, 72, 58, 63

References Cited UNITED STATES PATENTS 4/1969 Honnen et al. 44/723,671,511 6/1972 Honnen et al. 44/58 Primary Examiner-Daniel E. WymanAssistant E.\'am1'nerMrs. Y. H. Smith Attorney, Agent, or Firm-4}. F.Magdeburger; C. J. Tonkin; M. D. Nelson [57] ABSTRACT A mixture of highand low molecular weight hydrocarbyl amines exhibit excellent detergencyand dispersancy at low concentrations in fuels. The high molecularweight hydrocarbyl amine contains at least one hydrocarbyl group havinga molecular weight from about 1,900 to 5,000 and the low molecularweight hydrocarbyl amine contains at least one hydrocarbyl group havinga molecular weight from about 300 to 600. The weight ratio of lowmolecularweight amine to high molecular weight amine in the mixture ismaintained between about 0.5 and 5:1.

19 Claims, No Drawings HYDROCARBYLAMINE ADDITIVES FOR DISTILLATE FUELSCROSS-REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of U.S. ap plication Ser. No. 318,064, filed Dec.26, 1972, now abandoned, and Us application Ser. No. 318,063, filed Dec.26, 1972 now abandoned.

BACKGROUND OF THE INVENTION Field of the Invention Numerous depositforming substances are inherent in hydrocarbon fuels. These substanceswhen used in internal combustion engines tend to form deposits on andaround constricted areas of the engine contacted by the fuel. Typicalareas commonly and sometimes seriously burdened by the formation ofdeposits include carburetor ports, throttle body and venturies, engineintake valves, etc.

Deposits adversely affect the operation of the vehicle. For example,deposits on the carburetor throttle body and venturies increase the fuelto air ratio of the gas mixture to the combustion chamber therebyincreasing the amount of unburned hydrocarbon and carbon monoxidedischarged from the chamber. The high fuel-air ratio also reduces thegas mileage obtainable from the vehicle.

Deposits on the engine intake valves when they get sufficiently heavy,on the other hand, restrict the gas mixture flow into the combustionchamber. This restriction, starves the engine of air and fuel andresults in a loss of power. Deposits on the valves also increase theprobability of valve failure due to burning and improper valve seating.In addition, these deposits may break off and enter the combustionchamber possibly resulting in mechanical damage to the piston, pistonrings, engine head, etc.

The formation of these deposits can be inhibited as well as removed byincorporating an active detergent into the fuel. Numerous fueldetergents are currently available and many are commercially employed innational brand fuels. While these detergents function to varying degreesin cleaning carburetor throttle bodies and venturis or in maintainingintake valves with reduced deposits, or in cleaning other areas such asthe PCV valve, etc., only a few detergents are available to clean andmaintain all of the contacted areas effectively clean. Those detergentshaving this property as referred to hereinafter as a broad rangedetergent. Those few broad range detergents available must be employedat relatively high concentrations in order to maintain theireffectiveness. The employment of these high concentrations has theburdens of high costs and reduces the water tolerance properties of thefuel.

In addition to having the broad range detergent properties it is anadditional advantage of the fuel detergent to have dispersantproperties. In the operation of an internal combustion engine, a smallamount of the fuel additives inevitably finds access to the crankcaseand admixes with the crankcase oil. The continued presence of smallamounts of dispersants within the crankcase oil increases the ability ofthe oil to maintain sludges and the like dispersed. Thus, by developingan additive having both broad range detergency and dispersancy, thoseparts of the engine contacted by the fuel can be maintained effectivelyclean and, at the same time, those parts of the engine contacted by thecrankcase oil can be maintained with reduced sludge and varnishdeposits.

A class of fuel additives has recently been developed which exhibitsexcellent broad range detergency and good dispersancy. This class offuel detergentdispersant additives is commonly known as the polybuteneamines. Several patents disclosing the preparation and use of exemplarypolybutene amines include US. Pat. Nos. 3,438,757; 3,565,804; 3,574,576and 3,671,511. The polybutene amines disclosed in these patents exhibitremarkable broad range detergentdispersant properties and their use hassignificantly in creased the operating efficiency and has reduced themaintenance of vehicles operating on fuels containing the additive.

A problem appurtenant to the use of the polybutene amines is that ofadverse economics. The additives are normally employed at aconcentration between 250 and 400 parts per million for best results.Although these concentrations are relatively small, the use of theadditives in gasoline fuels which are sold in vast quantities at lowprofits results in a substantial cost burden to the petroleum fuelsuppliers. Thus, a reduction of the effective concentration of theadditive to the order of to 250 parts per million would result in aconsiderable economic savings.

It is therefore an object of this invention to provide a fuel additivehaving broad range detergent properties.

It is an additional object of this invention to provide a fuel additivehaving broad range detergent and dispersant properties.

It is another object of this invention to provide a fuel containing lowconcentrations of a detergentdispersant additive and having broad rangedetergent and dispersant properties.

It is an additional object of this invention to provide a fuelcontaining a broad range detergent which may be employed at lowconcentrations without sacrificing a loss in detergency obtained fromconventional detergents.

An additional object of this invention is to provide a method for makinga fuel having broad range detergent and dispersant properties.

Other objects of this invention will become apparent from the followingdescription of the invention and appended claims.

SUMMARY OF THE INVENTION I have found that the aforementioned objectsand their attendant advantages can be realized by incorporating into afuel an additive comprising a mixture of high and low molecular weighthydrocarbyl amines. The high molecular weight hydrocarbyl amines containat least one hydrocarbyl group having a molecular weight between about1,900 and 5,000. These amines may be conveniently prepared by reacting ahydrocarbyl halide having a molecular weight between about 1,900 and5,000 with a mono or polyamine having from 1 to 10 amine nitrogens andfrom 2 to 40 carbons with a carbon to nitrogen atomic ratio betweenabout 1 and 10:1. The low molecular weight hydrocarbyl amines contain atleast one hydrocarbyl group having a molecular weight between 300 and600. These amines may be prepared by reacting a hydrocarbyl halidehaving a molecular weight between about 300 and 600 with a mono orpolyamine having from 1 to 10 amine nitrogens and from 2 to 40 carbonswith a carbon to nitrogen atomic ratio between about 1 and 10:1 Theweight ratio of low to high molecular weight hydrocarbyl amines must bemaintained between about 0.5 and :1, although a ratio of l to 3:1 ispreferred.

While the exact mechanism of the combination of high and low molecularweight hydrocarbyl amines in effecting superior broad range detergencyand dispersancy is not completely understood, 1 have found that theparticular combination exhibits substantially the same excellentdetergency properties as the prior art polybutene amine detergents at asubstantially lower concentration. In some areas, the instantcombination exceeds the detergency of the prior art materials even whenemployed at the lower concentrations. Thus, the present invention is anadvancement in the automotive fuel additive area and representssignificant economic advantages.

DETAILED DESCRIPTION OF THE INVENTION The fuel composition of thisinvention contains a mixture of high and low molecular weighthydrocarbyl mono or polyamines or combinations thereof. As referred toherein, hydrocarbyl is a monovalent organic radical composedessentially, but not particularly entirely, of hydrogen and carbon andmay be aliphatic, aromatic or alicyclic or combinations thereof, e.g.,aralkyl, alkyl, alkylaryl, cycloalkyl, etc., and may be saturated orethylenically unsaturated. The preferred hydrocarbyls are aliphatic. Thehigh and low molecular weight amines generally, although notnecessarily, have the same general structure.

Both the high molecular weight and low molecular weight hydrocarbylamine may be conveniently prepared by reacting l a hydrocarbyl halidehaving from 1 to 5 halide atoms and less than percent of the availablesites substituted with a halogen atom with (2) a mono or polyaminehaving from I to 10 amine nitrogens with at least 1 primary or secondaryamino group and having from 2 to 40 carbon atoms with a carbon tonitrogen ratio betweenabout l and 10:1. The weight ratio of. lowmolecular weight hydrocarbyl amine to high molecular weight hydrocarbylamine within the mixture will generally vary from 0.5 to 5:1 preferably0.75 to 3:1 and more preferably from 1 to 3:1.

The high molecular weight hydrocarbyl halides may be prepared bynumerous commercially available processes. In a preferred embodiment,the hydrocarbyl portion maybe prepared by ionic or free radicalpolymerization of C to C mono olefins (when ethylene is employed it mustbev copolymerized with another higher olefin) to an olefin polymerhaving a number average molecular weight of 1,900 to 5,000, preferablyfrom 2,500 to 4,400, more preferably from 2,600 to 3,800. Exemplaryolefins which may be polymerized include ethylene, propylene,isobutylene, l-butene, lpentene, 3-methyll -pentene, 4-methyll -pentene,etc., and preferably propylene and isobutylene.

The olefin polymer should have, as an average, at least I branch per 6carbon atoms along the chain and preferably at least 1 branch per 4carbons. The preferred olefins (propylene and isobutylene) have from 0.5to l branch per carbon atom along the hydrocarbon chain.

While halogenating the olefin polymers is preferred, it is recognizedthat the high mol weight hydrocarbyl halides may be prepared byhalogenating lube oil fractions, paraffin waxes, etc.

The amount of halogen introduced will depend on the particularhydrocarbon used, the desired amount of amine to be introduced into themolecule, the particular alkylene amine used, and the halogen used.However, the amount of halogen introduced will generally be in the rangefrom about 1 to 5 halogen atoms per molecule, depending on thereactivity of the resulting halide. On a weight percent basis, theamount of halide will generally range from about 1 to 25, moreusuallyfrom about 1 to 10.

The low molecular weight hydrocarbyl halides may be prepared by the sameprocess as disclosed above for the high molecular weight hydrocarbylhalides. The polymerization, however, is conducted until an olefinpolymer having a number average molecular weight of 300 to 600,preferably from 300 to 550 and more preferably from 330 to 530 isprepared. The amount of halogen introduced into the olefin polymer willnormally vary from 1 to 2 halogen atoms per molecule. In an alternativeembodiment, the low mol weight hydrocarbons may be prepared by crackingthe high mol weight hydrocarbons. The high and low molecular weighthydrocarbyl halides may be prepared simultaneously within the samereaction medium or separately and thereafter combined to form anadmixture. This aspect is not critical to the practice of this inventionand numerous obvious alternative procedures are available to form themixture as claimed hereinafter.

Mono or Polyamine Component The mono or polyamine component embodies abroad class of amines having from 1 to 10 amine nitrogens and from 2 to40 carbons with a carbon to nitrogen ratio between about land 10:1. Inmost instances, the amine component is not a pure single product, butrather a mixture of compounds having a major quantity of the designatedamine. For the more complicated polyamines, the compositions will be amixture of amines having as the major product the compound indicated inthe average composition and having minor amounts of analogous compoundsrelatively close in compositions to the dominant compounds.

It should be noted, that while I referred to the mixture of thisinvention as hydrocarbyl amines, it does not mean that these amines aremade solely of carbon, hydrogen and amino nitrogen. For example, thecompounds may contain minor amounts of oxygen, sulfur, non-aminonitrogen, etc., and may include small amounts of halogen.

The preferred mono and polyamine components will have the followinggeneralized chemical formula:

wherein R is the same or different constituent selected from hydrogen,hydrocarbyl or hydroc'arboyl having from 1 to carbons and preferablyaliphatic from I to 6 carbons, and inclusive of the mono-keto,mono-nitro, mono-hydroxy, hydrocarbonyl, alkoxy, or alkyleneoxy,derivative thereof and preferably the monohydroxy or polyalkyleneoxyderivative, and at least one of said R groups is hydrogen.

R is the same or different alkylene or hydroxy substituted alkylenehaving from 2 to 6 carbons and preferably from 2 to 3 carbons;

a is an integer from O to l and preferably 1;

b is an integer from 0 to 4 and preferably from 0 to c is an integerfrom 0 to 1 and preferably 0;

d is an integer from 0 to l and preferably 1;

e is an integer from O to 1 and preferably 1; and

f is an integer from O to 1 and equal to 1 when 0 is As employed herein,the recitation the same or different means that the same type ordifferent group may be employed.

Exemplary R groups include alkyls such as methyl, ethyl, propyl, butyl,isobutyl, pentyl, hexyl, octyl, etc., alkenyls such as propenyl,isobutenyl, hexenyl, octengyl, etc., hydroxyalkyls, such as2-hydroxyethyl, 3- hydroxypropyl, hydroxy-isopropyl, 4-hydroxybutyl, 8-hydroxyoctyl, etc., ketoalkyls such as 2-ketopropyl, 6- ketooctyl, etc.,alkoxy and alkyleneoxy alkyls, such as ethoxyethyl, ethoxypropylpropoxyethyl, propoxypropyl, diethyleneoxyethyl, triethyleneoxyethyl,tetraethyleneoxyethyl, diethyleneoxyhexyl, diethyleneoxyoctyl, etc.,acetyls such as propionyl, etc. The preferred R groups are hydrogen, Cto C alkyls and C to C hydroxyalkyls.

Illustrative R, groups are ethylene, l,2-propylene, 2,2-dimethylpropylene, trimethylene, tetramethylene, hexamethylene, etc. Thepreferred alkylene groups are ethylene and trimethylene.

As already indicated, in many instances a single compound will not beused as a reactant in the preparation of the compositions of thisinvention. That is, mixtures will be used in which one or two compoundswill predominate with the average composition or molecular weight asindicated. For example, tetraethylcne pentamine prepared by thepolymerization of aziridine or reaction of dichloroethylene and ammoniawill have both lower and higher amino members, e.g., triethylenetetramine, substituted piperazines and pentaethylene hexamine, but thecomposition will be mainly tetraethylene pentamine and the empiricalformula of the total composition will closely approximate that oftetraethylene pentamine.

The high and low molecular weight hydrocarbyl amines are readilyprepared by combining the high and low molecular weight hydrocarbylhalides with the desired mono or polyamine in the proper molproportions. The two hydrocarbyl amine reactants may be reactedsimultaneously with the amine co-reactant in the same reaction medium,or alternatively, each may be reacted with an amine in a separatereaction medium H i P H 1'.

and thereafter combined to form the mixture of this invention.

The reaction or reactions may be conducted with or without the presenceof a reaction solvent. A reaction solvent is generally employed whenevernecessary to reduce the viscosity of the reaction product. Thesesolvents should be stable and inert to the reactants and reactionproduct. Preferred solvents include aliphatic or aromatic hydrocarbons.Aliphatic alcohols may be used alone or in combination with anotherinert solvent.

The reaction may be carried out at room temperature (20C.), but elevatedtemperatures are preferred. Usually, the temperature will be in therange of from about to 225C. Depending on the temperature of thereaction, the particular halogen used, the mol ratios and the particularamine, as well as the reactant concentrations, the time may vary from 1to 24 hours, more usually from about 2 to 10 hours. Times greatly inexcess of 10 hours do not particularly enhance the yield and may lead toundesirably degradation. It is therefore preferred to limit the reactiontime to fewer than 10 hours. i

The mol ratio of the hydrocarbyl halides to amine will generally be inthe range from about 0.2 to 20 mols of amine per mol of hydrocarbylhalide, and more usually 0.5 to 10 mols of amine per mol of hydrocarbylhalide. The mol ratio will depend upon the amount of halogen present inthe hydrocarbyl halide, the particular halogen and the desired ratio ofhydrocarbon to amine. lf complete suppression of polysubstitution of thealkylene polyamines is desired, then large mol excesses of the aminewill be used.

Small amount of residual halogen in the final composition are notdeleterious. Generally, the residual halogen as bound halogen will be inthe range of 0 to 10 weight percent of the composition. Small amounts ofhalogen may be present as the hydrohalide salt of the hydrocarbonsubstituted alkylene polyamines.

After the reaction has been carried out for a sufficient length of time,the reaction mixture may be subjected to extraction with a hydrocarbonmedium to free the product from any low molecular weight amine saltswhich have formed and any unreacted alkylene polyamines. The product maythen be isolated by evaporation of the solvent. Further separation fromunreacted hydrocarbyl halides and amines or purification may be carriedout as desired.

Depending on the particular application of the composition of thisinvention, the reaction may be carried out in the medium in which itwill ultimately find use. and be formed at concentrations which providea concentrate of the detergent composition. Thus, the final mixture maybe in a form to be used directly for blending in fuels. 1

A more detailed description of a process for preparing the hydrocarbylamines is described in U.S. Pat. No. 3,671,51 1. This process may beemployed in preparing the hydrocarbyl amine mixture of this invention.and the description is herein incorporated by reference.

The preferred, but not all, high and low molecular weight hydrocarbylamines which finds use in this in- 7 vention can be broadly described bythe following general formula:

wherein U is an alkylene having from 2 to 6 carbon atoms,

there being at least 2 carbon atoms between the nitrogen atoms andpreferably of from 2 to 3 carbon atoms;

u is an integer from to 5. and preferably of from 0 b is an integer from0 to 1, preferably 0 when a is greater than 0;

a 2b is equal to an integer between 0 and 5;

c is an integer from l to 4, for the average composition being in therange of about 1 to 3, on the average there being fewer R groups thannitrogen atoms;

R is the same or different constituent selected from hydrogen or a C toC hydrocarbyl or the monoketo, mono-nitro, monohydroxy, alkyleneoxy oralkoxy derivative thereof; and R is a branched chain aliphatichydrocarbon radical derived from polymerizing olefins from 2 to 6 carbonatoms, preferably from 3 to 4 carbon atoms, and more preferable frompropylene and isobutylene and having an average molecular weight in therange of 1,900 to 5,000 for the high molecular weight component and 300to 600 for the low molecular weight component.

Illustrative compounds within the above formula are as follows:N-polyisobutenyl ethylene diamine, N- polypropenyl ethylene diamine.N-poly( 1-butenyl)'ethylene diamine, N-(alternating copolymer ofethylene and isobutylene) ethylene diamine (alternating copolymers ofethylene and isobutylene may be achieved by the cationic polymerizationof 4-methylpentene-1 N- polypropenyl Z-aminoethylpiperazine, N-polyisobutenyl Z-aminoethylpiperazine, N- polypropenyl dicthylenetriamine, N-polyisobutenyl diethylene triamine, N-poly(1-pentenyl)diethylene triamine, N-polypropenyl trimethylenc diamine, N-polyisobutenyl trimethylene diaminc. N-polypropenyl di( trimcthylene)triaminc, N-polyisobutenyl di- (trimethylene )triamine, N-polyisobutenyl1.2- propylene diamine, N-polyisobutenyl di( 1,2-

N in) The above symbols are defined as follows: a is an integer from 0to 5, preferably an integer of from 0 to 4;

b is an integer from O to 1, preferably 0 when a is greater than 0;

a 2b is equal to a number between 0 and 5;

c is an integer in the range of 1 to 3, on the average there being fewerR groups than nitrogen atoms;

f is an integer from 2 to 3;

R is the same or different constituent selected from hydrogen on a C toC hydrocarbyl or the monoketo, mononitro, monohydroxy, alkyleneoxy oralkoxy derivative thereof; and

R is a branched chain aliphatic hydrocarbon radical either free of orhaving aliphatic unsaturation, e.g., olefinic, and from 1,900 to 5,000average molecular weight for the high molecular weight component andfrom 300 to about 600 average molecular weight for the low molecularweight component.

The above formulae represent broad and simplified versions of thepreferred hydrocarbyl amines which may be employed in the practice ofthe instant invention. It should be recognized that numerous high andlow molecular weight hydrocarbyl amines not defined by the aboveformulae may be present in minor quantities. Thus, while the aboveformulae define preferred hydrocarbyl amines present in majorquantities, they should not be interpreted as excluding minor amounts ofother components.

The mixture of hydrocarbyl amines will generally be employed in ahydrocarbon distillate fuel. The proper concentration of additivenecessary in order to achieve the desired detergency and dispersancyvaries depending upon the type of fuel employed, the presence of otherdetergents, dispersants and other additives, etc. Generally. however,from to 300 weight parts per million, preferably from 150 to 250 ppm andmore preferably from to 250 ppm of hydrocarbyl amine mixture per part ofbase fuel is needed to achieve the best results. When other detergentsare present, a lesser amount of hydrocarbyl amine mixture is required toa minimum of 50 parts per million. When other hydrocarbyl amines arepresent within the fuel composition. these amines are included incalculating the critical ratio of high and low molecular weight amines.

The detergent additive may be formulated as a concentrate, using aninert stable oleophilic organic solvent boiling in the range of about150 to 400F. Preferably, an aliphatic or an aromatic hydrocarbon solventis used, such as benzene, toluene, xylene or higher boiling aromatics oraromatic thinners. Aliphatic alcohols of about 3 to 8 carbon atoms, suchas isopropanol, isobutylcarbinol, n-butanol and the like, in combinationwith hydrocarbon solvents are also suitable for use with the detergentadditive. ln theconcentrate, the amount of the additive will beordinarily at least 10 percent by weight and generally not exceed 7 0percent by weight and preferably from 20 to 60 weight percent.

In gasoline fuels, other fuel additives may also be included such asantiknock agents, e.g., tetramethyl lead or tetraethyl lead, or otherdispersants such as various substituted succinimides, etc. Also includedmay be lead scavengers such as aryl halides. e.g., dichlorobenzene oralkyl halides, e.g., ethylene dibromide. Additionally, anti-oxidants maybe present.

A particularly useful additive is a fuel soluble carrier oil. Exemplarycarrier oils include nonvolatile lubricat ing mineral oil, e.g.,petroleum spray oil, particularly a refined naphthenic lubricating oilhaving a viscosity at 378C. 100F.) of 1,000 to 2,000 SUS. Other carrieroils which may be employed include paraffin bright stocks, or solventrefined paraffin distillate oils, having a viscosity index of 80 to 100,polyolefins such as polyisobutene, polypropylene, etc., polyalkoxypolyols and polyamines such as the Pluronics and Tetronics marketed byWyandotte Chemical Corporation. When used, these oils are believed toact as a carrier for the detergent and assist in removing and retardingdeposits. They are employed in amounts from about 0.05 to 0.5 percent byvolume, based on the final gasoline composition.

The mixture of high and low molecular weight hydrocarbyl amines may alsobe used as dispersants and detergents in lubricating oils. Lubricatingoils which may be employed include a wide variety of natural andsynthetic oils such as naphthenic base, paraffin base and mixed baselubricating oils. The oils generally have a viscosity of 35 to 50,000SUS at 378C. (100F.).

The following examples are presented to illustrate specific embodimentsof the practice of this invention and should not be interpreted aslimitations upon the scope of the invention.

EXAMPLE 1 A low molecular weight hydrocarbyl halide is prepared bycharging 1,526 grams of polyisobutylene having a number averagemolecular weight of about 530 dissolved in 205 ml of benzene. Themixture is stirred and chlorine is introduced at a rate of about 330 mlper minute. The temperature of the reaction meduim is maintained at 72C.After the reaction mixture has taken up 137 grams of chlorine, theintroduction of chlorine is terminated, the benzene solvent removed byvacuum distillation and the chlorinated polyisobutylene isolated andanalyzed. Analysis reveals approximately 8.19 weight percent chlorine.

EXAMPLE 2 A high molecular weight hydrocarbyl halide is prepared bycharging 5,000 grams of polyisobutylene having a molecular weight ofabout 2,700 dissolved in 2,300 grams of benzene. The mixture is stirredand chlorine is introduced at a rate of about 525 ml per minute. Thetemperature of the reaction medium is maintained at about 70C. Afterabout 300 minutes the reaction is terminated, the benzene solventremoved by vacuum distillation and the chlorinated polyisobutyleneisolated and analyzed. Analysis reveals approximately 2.55 weightpercent chlorine.

EXAMPLE 3 A high molecular weight hydrocarbyl amine is prepared bycharging into a reaction vessel 2,000 grams of a 69 wt solution of thechlorinated polyisobutylene in benzene prepared by the method of Example2 and 345 grams of ethylene diamine. The mixture is then heated toreflux at a temperature of 80C. and benzene allowed to distill overhead.Thereafter, the mixture is heated to 150C. for 2 hours. The crudeproduct weight 1,670 grams. The product is then washed by adding 1,670grams of xylene and 417 grams of n-butanol, heated to reflux and 845grams of a 3 wt aqueous sodium hydroxide solution added. The mixture isheated and stirred for 5 minutes at reflux and thereafter al lowed tophase separate. The organic phase is recovered and washed two times with845 grams of an aqueous 3 wt n-butanol solution. All of the solvents areremoved by vacuum distillation and the product analyzed. An elementalanalysis of the product reveals 0.79 wt nitrogen and a conversion toactive product of 76 wt.

EXAMPLE 4 A low molecular weight hydrocarbyl amine is prepared bycharging into a reaction vessel 1,000 grams of an 88 wt solution of thechlorinated polyisobutylene in benzene prepared by the method of Example1 and 540 grams of ethylene diamine. The mixture is then heated to atemperature of 150C. allowing benzene and excess ethylene diamine todistill overhead. The temperature is maintained at 150C. for 2 hours.The resulting crude product is washed by the procedure set forth in theabove Example 3. The volatile materials are stripped from the mixture byvacuum distillation. An elemental analysis of the product reveals 3.92wt. nitrogen and a conversion of 87.5%.

EXAMPLE 5 The effectiveness of the high and low mol weight hydrocarbylamine mixture in reducing harmful engine valve deposits is illustratedby this ASTM/CFR singlecylinder engine test. ln carrying out the tests,a Waukesha CFR single-cylinder engine is used. The run is carried outfor 10 hours, at the end of which time the intake valve, is removed,washed with hexane and weighed. The deposits are removed with a wirebrush and the valve reweighed. The differences between the two weightsis the weight of the deposit with a lesser amount of deposit measuredconnoting a superior additive. The operating conditions of the test areas follows: water jacket temperature C. (212F.); manifold vacuum of 15in Hg, intake mixture temperature of 52C. (F.): air-fuel ratio of 14;ignition spark timing of 15 BTC; engine speed is 1,800 rpm; thecrankcase oil is a commercial CHEVRON 30W oil. The amount ofcarbonaceous deposit in milligrams on the intake valves is measured andreported in the following Table I.

The base fuel tested in the above extended detergency test is a regularoctane gasoline containing no fuel detergent. The base fuel is admixedwith varying amounts of detergent additives. Additive A is a polybuteneamine prepared by reacting (l) a'polyisobutene chloride having a numberaverage molecular weight in the polyisobutene portion of about 1,400 anda chlorine content of about 4wt. with (2) ethylene diamine. Additive Bis a mixture of low and high molecular weight polyisobutene aminesprepared by the method of examples 3 and 4, respectively. Additive C isthe same as Additive B above except that a different ratio of low tohigh molecular weight polyisobutene amines is employed. Each of theabove fuels containing a detergent additive contains about 4 parts of acarrier oil (a napthenic hydrofmed pale oil with a viscosity at 378C.(100F.) of 1,800 SUS).

The results of the engine valve deposit tests with the above additivesare presented in the following Table I.

TABLE 1 INTAKE VALVE DEPOSIT TESTS "'Wcight ratio of low molecularweight to high molecular weight polybutene amine present in theadditive.

The above table illustrates a large improvement in reduced valvedeposits of additives B and C over Additive A, particularly at aconcentration of 150 ppm. At the 150 ppm concentration, Additive Cillustrates a greater than six-fold reduction in valve deposits overAdditive A. Additive B illustrates a greater than twofold reduction overAdditive A.

EXAMPLE 6 This example is presented to hypothetically illustrate severaldetergent-dispersant mixtures of this invention. The compositions arebelieved to exhibit the same excellent detergency and good dispersancyproperties at low concentrations. The fuel composition is composed ofvarying amounts of the detergent-dispersant mixture in a hydrocarbondistillate fuel boiling between about 30C. (85F.) and 216C. (420F.).Representative compositions are illustrated by the following Table 11.

TABLE I1 REPRESENTATIVE COMPOSITIONS Polybutene Amine Additive HighMolecular Weight Low Molecular Weight ple. A 2-liter glass pot ischarged with 200 grams of the polybutene chloride solution 12% benzene)prepared by the method of Example 1 and 200 grams of monoethanol amine.The contents are stirred and heated to a temperature of 150C andmaintained at that temperature for 3 hours. The crude product is washedin the same manner as described in Example 3 and the solvents removed byvacuum distillation. An elemental analysis of the product reveals 1.99wt. nitrogen with a conversion to active product of 84.7 percent.

EXAMPLE 8 The preparation of a high mol weight hydrocarbyl monoethanolamine is illustrated in this example. A 2- liter glass pot is chargedwith 880 grams of the polybutene chloride solution (31% benzene)prepared by the method of Example 2 and 45 grams of monoethanol amine.The contents are stirred and heated to 150C and maintained at thetemperature for 5 hours. The crude product is washed in the same manneras described in Example 3 and the solvent removed by vacuumdistillation. An elemental analysis of the product reveals 0.49 Wt.nitrogen.

EXAMPLE 9 A fuel blend is prepared by admixing into a detergent-freeleaded regular gasoline, 130 ppm (parts per million) of the lowmolecular weight hydrocarbylmonoethanol amine prepared by the method ofExample 7, 56 ppm of the high molecular weight hydrocarbyl-monoethanolamine prepared by the method of Example 8 and 1,000 ppm of a hydrocarboncarrier oil (a naphthenic lube oil having a viscosity of about 1,800 SUSat 37.8C 100F)). The fuel blend is tested in the Intake Valve DepositTest as described in Example 5 to reveal a valve deposit of 38 mg.

EXAMPLE 10 The preparation of a low molecular weightdimethylaminopropylamine is illustrated in this example. A

Other Additives Composition Type MW Type MW Type 1 PBEDA 2700 PBEDA 5 302 PBEDA 2700 PBEDA 530 TEL 3 PBEDA 2700 PBEDA 530 TEL 4 PBEDA 2500 PBEDA530 5 PBEDA 2500 PBEDA 440 6 PBEDA 4300 PBEDA 5 30 7 PBEDA 4300 PBEDA440 8 PBEDA 4300 PBEDA 330 9 PBDETA" 2700 PBDETA 5 30 1O PBTETA 2700PBTETA 5 3O 1 1 PBTEPA" 2700 PBTEPA 530 12 PBTEPA 2700 PBEDA 530 13PBDEA 2700 PBDEA 530 "Number average molecular weight of the hydrocarbonportion of the molecule.

"-PBEDA is polybutene (PB) ethylene diamine prepared by reactingpolyhutene halide with ethylene diamine.

"Tctraethyl lead.

*PBDETA is polybutenc diethylene triamine. ""PBTETA is polybutenetriethylene tetraaminc.

"" PBTEPA is polyhutene tctraethylene pcntaaminc. "'PBDEA is polyhutenediethanol amine.

EXAMPLE 7 The preparation of a low molecular weight hydrocarbylmonoethanol amine is illustrated in this exam- NH The contents areheated to reflux and the solvents removed until the temperature attains150C. The contents are maintained at a temperature between l50l70C for 4hours and thereafter allowed to cool and admixed with an equal volume ofhexane. The contents are washed 3 times with 3 parts of water, 1 partethanol and 0.1 part of butanol per part by volume of crude product. Thesolvents are stripped by vacuum distillation and a sample of the productanalyzed. The base number is measured at 158 mg KOH/gram and thenitrogen content measured at 3.97 wt.

EXAMPLE 1 1 The preparation of a high molecular weight dimethylamino-propylamine is illustrated in this example. A l-liter glassreaction vessel is charged with 700 grams of the polybutene chloridesolution (31% benzene) prepared by the method of Example 2 and 61 gramsof dimethylamino-propylamine. The contents are heated to reflux and thebenzene solvent removed until the temperature of the reaction mediumattains 150C. The contents are maintained at this temperature for 4hours, thereafter cooled and admixed with an equal volume of hexane. Thecrude product is washed in the same manner as described in Example andthe solvents removed by vacuum distillation. The final product contained0.79 wt. nitrogen upon analysis and had a base number of 30 mgKOl-l/gram.

EXAMPLE 12 A fuel blend is prepared by admixing into a detergent-freeregular gasoline, 214 ppm of a low molecular weight hydrocarbyl amineprepared by the method of Example 10 and 93 ppm ofa high molecularweight hydrocarbyl amine prepared by the method of Example 1 1 alongwith 1,000 ppm pf a carrier oil of the type employed in Example 9.

EXAMPLE 13 The preparation of a low molecular weight hydrocarbylhydroxyethyl ethylene diamine is illustrated in this example. Thereaction procedure and washing steps are the same herein as are recitedfor Example 10. The following amounts are employed 200 grams ofpolybutene chloride solution as prepared in Example 1, 124 grams ofhydroxyethyl ethylene diamine [NH Cl-l NHCH Ol-l] The resulting finalproduct has a base number of 1 1 1 mg KOH/gram and a nitrogen content of3.29 wt.

EXAMPLE 14 The preparation of a high molecular weight hydrocarbylhydroxyethyl ethylene diamine is illustrated in this example. Thereaction procedure and washing steps are the same herein as are recitedfor Example 10. The following amounts are employed 703 grams ofpolybutene chloride solution as prepared in Example 2, 62 grams ofhydroxyethyl ethylene diamine. The resulting final product has a basenumber of 19 mg KOHlgram and a nitrogen content of 0.72 wt.

EXAMPLE A hypothetical fuel blend is prepared by blending in a leadedpremium gasoline 150 ppm of active low molecular weight hydrocarbylamine prepared by the method of Example 13 and 50 ppm of active highmolecular weight amine prepared by the method of Example l5 and 800 ppmof a polybutene carrier oil having a viscosity of about 200 SUS at F.

EXAMPLE 16 The preparation of a low molecular weight hydrocarbyldiethanol amine-monoethanol amine is illustrated in this example. A2-liter glass pot is charged with 85 grams of a polybutene chloridesolution (12% benzene) as prepared by Example 1 and 16.4 grams ofdiethanol amine. The contents are heated to C and maintaind at thattemperature for 10 minutes while the benzene solvent is removedoverhead. Thereafter 37.4 grams of monoethanol amine are charged to thepot and the temperature maintained at 150C for 2 hours. The crudeproduct is cooled and washed in accordance with the wash steps recitedin Example 3. The product is analyzed and found to contain 1.78 wt.nitrogen.

EXAMPLE 1 7 The hypothetical preparation of a high molecular weighthydrocarbyl diethanol amine-monoethanol amine is illustrated in thisexample. The reaction procedure and washing steps are the, same asrecited above for Example 16. The following amounts are employed: 400grams of polybutene chloride solution as prepared by Example 2, 20.8grams of diethanol amine and 36 grams of monoethanol amine. at the endof the washing steps, the solvents are removed by vacuum distillation.

EXAMPLE 1 8 A hypothetical fuel composition is prepared by blending in aleaded regular gasoline, ppm of active low molecular weight hydrocarbylamine as prepared by Example 16; 75 ppm of active high molecular weighthydrocarbyl amine as prepared by Example 17 and 1,000 ppm of a carrieroil as defined in Example I claim:

1. A fuel composition of a distillate fuel containing from 150 to 300parts per million of a mixture of a high molecular weight hydrocarbylamine and a low molecular weight hydrocarbyl amine wherein a weightratio of low to high molecular weight amine present within said mixtureis between about 0.5 and 5:1; said high molecular weight hydrocarbylamine being prepared by reacting a first hydrocarbyl halide having anumber average molecular weight in the hydrocarbyl portion of 1,900 to5,000 with a monoor polyamine having from 1 to 10 amine nitrogens andfrom 2 to 40 carbons with a carbon to nitrogen atomic ratio betweenabout 1 and 10:1; and said low molecular weight hydrocarbyl amine beingprepared by reacting a second hydrocarbyl halide having a number averagemolecular weight in said second hydrocarbyl portion of 300 to 600 with amonoor polyamine having from 1 to 10 amine nitrogens and from 2 to 40carbons with a carbon to nitrogen atomic ratio between about 1 and 10:1.

2. The fuel composition defined in claim 1 wherein said high and lowmolecular weight hydrocarbyl amines are present in an amount from 1 to 3weight parts of low molecular weight amine per weight part of highmolecular weight amine.

3. The fuel composition defined in claim 1 wherein from 0.05 to 0.5volume percent of a fuel-soluble inert carrier oil is incorporated intosaid distillate fuel.

4. The fuel composition defined in claim 3 wherein I said carrier oil isselected from a naphthenic lubricating oil having a viscosity at 100F of1,000 to 2,000 SUS, a paraffinic bright stock having a viscosity indexbetween 80 and 100, polyolefins and polyalkoxy polyols.

5. A fuel composition comprising a distillate fuel containing from 150to 300 parts per million of a mixture of high and low molecular weighthydrocarbyl amines wherein said hydrocarbyl amines are prepared byreacting a high molecular weight hydrocarbyl halide having a numberaverage molecular weight in the hydrocarbyl portion of 2,500 to 4,400and a low molecular weight hydrocarbyl halide having a number averagemolecular weight in the hydrocarbyl portion of 300 to 550 with the sameor a different amine having the following general structural formula:

wherein R is the same or different constituent selected from hydrogen,hydrocarbyl or hydrocarboyl having from l to 10 carbons and at least oneof said R groups in said amine is hydrogen;

R is the same or different alkylene or hydroxy substituted alkylenehaving from 2 to 6 carbons;

a is an integer from to l;

b is an integer from 0 to 4;

c is an integer from 0 to 1;

d is an integer from 0 to 1;

e is an integer from 0 to 1;

f is an integer from 0 to 1 and equal to 1 when 4" is 0 said lowmolecular weight hydrocarbyl amine is present in an amount from 0.5 to 5parts by weight per weight part of said molecular weight hydrocarbylamine.

6. The composition defined in claim 5 wherein said b is zero and saidhigh molecular hydrocarbyl halide has a number average molecular weightin the hydrocarbyl portion of 2,600 to 3,800.

7. The composition defined in claim 5 wherein said amine is ethylenediamine.

8. The composition defined in claim 5 wherein said high molecular weighthydrocarbyl halide is a hydrocarbyl chloride having a number averagemolecular weight in the hydrocarbyl portion of about 2,700 and whereinsaid low molecular weight hydrocarbyl halide is a hydrocarbyl chloridehaving a number average molecular weight in the hydrocarbyl portion ofabout 530.

9. The composition defined in claim 8 wherein said high and lowmolecular weight amines are present in an amount from 1 to 3 weightparts of low molecular weight amine per weight part of high molecularweight amine.

10. The fuel composition defined in claim 5 wherein from 0.05 to 0.5volume percent of a fuel-soluble inert carrier oil is incorporated intosaid distillate fuel.

11. The fuel composition defined in claim 10 wherein said carrier oil isselected from a naphthenic lubricating oil having a viscosity of 100F of1,000 to 2,000SUS, polyolefins, polyalkoxy polyols and a paraffinicbright stock having a viscosity index between 80 and 100.

12. A gasoline composition comprising a major portion of a petroleumdistillate fuel boiling in the gasoline range and in an amountsufficient to provide detergency and dispersancy of to 300 ppm of amixture of high and low molecular weight hydrocarbyl amines prepared byreacting a high molecular weight hydrocarbyl halide having a numberaverage molecular weight in the hydrocarbyl portion of 1,900 to 5,000and a low molecular weight hydrocarbyl halide having a number averagemolecular weight in the hydrocarbyl portion of 300 to 600 with the sameor a different amine having the following general structural formula:

wherein R is the same or different constituent selected from hydrogen,hydrocarbyl or hydrocarboyl having from 1 to 10 carbons and at least oneof said R groups in said amine is hydrogen;

R is the same or different alkylene or hydroxy substituted alkylenehaving from 2 to 6 carbons;

a is an integer from 0 to 1;

b is an integer from 0 to 4;

is an integer from 0 to l; d is an integer from 0 to 1; e is an integerfrom 0 to 1;

j is an integer from 0 to l and equal to 1 when 0 is 0 said lowmolecular weight hydrocarbyl amine is present in an amount from 0.5 to 5parts by weight per weight part of said high molecular weighthydrocarbyl amine.

13. The gasoline composition as defined in claim 12 wherein said highand low molecular weight amines are present in an amount from 1 to 3weight parts of low molecular weight amine per weight part of highmolecular weight amine.

14. The gasoline composition as defined in claim 12 wherein said highmolecular weight hydrocarbyl halide is a hydrocarbyl chloride having anumber average molecular weight in the hydrocarbyl portion of about2,700 and wherein said low molecular weight hydrocarbyl halide is ahydrocarbyl chloride having a number average molecular weight in thehydrocarbyl portion of about 530.

15. A gasoline composition defined in claim 12 wherein from 0.05 to 0.5volume percent ofa gasolinesoluble inert carrier oil is incorporatedinto said composition.

16. A fuel composition comprising a distillate fuel containing from 150to 300 parts per millionof a mixture of high and low molecular weighthydrocarbyl amines having the general formula:

wherein U is an alkylene having from 2 to 6 carbons;

a is an integer from to b is an integer from 0 to l;

a+2b is equal to an integer between 0 and 5;

c is an integer from 1 to 4;

R is the same or different constituent selected from hydrogen or a C toC hydrocarbyl;

R is a branched chain aliphatic hydrocarbon radical having an averagemolecular weight in the range of 2,500 to 4,400 for the high molecularweight hydrocarbyl amine and 300 to 500 for the low molecular weighthydrocarbyl amine; the ratio of low to high molecular weight hydrocarbylamines in the mixture being within the range of 0.5 to 5:1.

17. The gasoline composition defined in claim 16 wherein said highmolecular weight amine is polyisobutenyl having an average molecularweight in the polyisobutenyl portion of 2,500 to 4,400 ethylene diamineand said low molecular weight amine is polyiso-; butenyl ethylenediamine having an average molecularf weight in the polyisobutenylportion of 300 to 550. i

18. A gasoline composition defined in claim 16 wherein from 0.05 to 0.5volume percent of a gasolinesoluble inert carrier oil is incorporatedinto said composition.

19. A gasoline composition containing a mixture of high and lowmolecular weight hydrocarbyl monoor polyamines; said high molecularweight hydrocarbyl amine containing at least one hydrocarbyl grouphaving a molecular weight from 1,900 to 5,000 and said low molecularweight hydrocarbyl amine containing at least one hydrocarbyl grouphaving a molecular weight from 300 to 600; the weight ratio of said lowmolecular weight hydrocarbyl amine to said high molecular weighthydrocarbyl amine is between about 0.5 and 5:1.

1. A FUEL COMPOSITION OF A DISTILLATE FUEL CONTAINING FROM 150 TO 300PARTS PER MILLION OF A MIXTURE OF A HIGH MOLECULAR WEIGHT HYDROCARBYLAMINE AND A LOW MOLECULAR WEIGHT HYDROCARBYL AMINE WHEREIN A WEIGHTRATIO OF LOW TO HIGH MOLECULAR WEIGHT AMINE PRESENT WITHIN SAID MIXTUREIS BETWEEN ABOUT 0.5 AND 5:1, SAID HIGH MOLECULAR WEIGHT HYDROCARBYLAMINE BEING PREPARED BY REACTING A FIRST HYDROCARBYL HALIDE HAVING ANUMBER AVERAGE MOLECULAR WEIGHT IN THE HYDROCARBYL PORTION OF 1,900 TO5,000 WITH A MONO- OR POLYAMINE HAVING FROM 1 TO 10 AMINE NITROGENS ANDFROM 2 TO 40 CARBONS WITH A CARBON TO NITROGEN ATOMIC RATIO BETWEENABOUT 1 AND 10:1, AND SAID LOW MOLECULAR WEIGHT HYDROCARBYL AMINE BEINGPREPARED BY REACTING A SECOND HYDROCARBYL HALIDE HAVING A NUMBER AVERAGEMOLECULAR WEIGHT IN SAID SECOND HYDROCARBYL PORTION OF 300 TO 600 WITH AMONO- OR POLYAMINE HAVING FROM 1 TO 10 AMINE NITROGENS AND FROM 2 TO 40CARBONS WITH A CARBON TO NITROGEN ATOMIC RATIO BETWEEN ABOUT 1 AND 10:1.2. The fuel composition defined in claim 1 wherein said high and lowmolecular weight hydrocarbyl amines are present in an amount from 1 to 3weight parts of low molecular weight amine per weight part of highmolecular weight amine.
 3. The fuel composition defined in claim 1wherein from 0.05 to 0.5 volume percent of a fuel-soluble inert carrieroil is incorporated into said distillate fuel.
 4. The fuel compositiondefined in claim 3 wherein said carrier oil is selected from anaphthenic lubricating oil having a viscosity at 100*F of 1,000 to 2,000SUS, a paraffinic bright stock having a viscosity index between 80 and100, polyolefins and polyalkoxy polyols.
 5. A fuel compositioncomprising a distillate fuel containing from 150 to 300 parts permillion of a mixture of high and low molecular weight hydrocarbyl amineswherein said hydrocarbyl amines are prepared by reacting a highmolecular weight hydrocarbyl halide having a number average molecularweight in the hydrocarbyl portion of 2,500 to 4,400 and a low molecularweight hydrocarbyl halide having a number average molecular weight inthe hydrocarbyl portion of 300 to 550 with the same or a different aminehaving the following general structural formula:
 6. The compositiondefined in claim 5 wherein said b'' is zero and said high molecularhydrocarbyl halide has a number average molecular weight in thehydrocarbyl portion of 2,600 to 3,800.
 7. The composition defined inclaim 5 wherein said amine is ethylene diamine.
 8. The compositiondefined in claim 5 wherein said high molecular weight hydrocarbyl halideis a hydrocarbyl chloride having a number average molecular weight inthe hydrocarbyl portion of about 2,700 and wherein said low molecularweight hydrocarbyl halide is a hydrocarbyl chloride having a numberaverage molecular weight in the hydrocarbyl portion of about
 530. 9. Thecomposition defined in claim 8 wherein said high and low molecularweight amines are present in an amount from 1 to 3 weight parts of lowmolecular weight amine per weight part of high molecular weight amine.10. The fuel composition defined in claim 5 wherein from 0.05 to 0.5volume percent of a fuel-soluble inert carrier oil is incorporated intosaid distillate fuel.
 11. The fuel composition defined in claim 10wherein said carrier oil is selected from a naphthenic lubricating oilhaving a viscosity of 100*F of 1,000 to 2,000SUS, polyolefins,polyalkoxy polyols and a paraffinic bright stock having a viscosityindex between 80 and
 100. 12. A gasoline composition comprising a majorportion of a petroleum distillate fuel boiling in the gasoline range andin an amount sufficient to provide detergency and dispersancy of 150 to300 ppm of a mixture of high and low molecular weight hydrocarbyl aminesprepared by reacting a high molecular weight hydrocarbyl halide having anumber average molecular weight in the hydrocarbyl portion of 1,900 to5,000 and a low molecular weight hydrocarbyl halide having a numberaverage molecular weight in the hydrocarbyl portion of 300 to 600 withthe same or a different amine having the following general structuralformula:
 13. The gasoline composition as defined in claim 12 whereinsaid high and low molecular weight amines are present in an amount from1 to 3 weight parts of low molecular weight amine per weight part ofhigh molecular weight amine.
 14. The gasoline composition as defined inclaim 12 wherein said high molecular weight hydroCarbyl halide is ahydrocarbyl chloride having a number average molecular weight in thehydrocarbyl portion of about 2,700 and wherein said low molecular weighthydrocarbyl halide is a hydrocarbyl chloride having a number averagemolecular weight in the hydrocarbyl portion of about
 530. 15. A gasolinecomposition defined in claim 12 wherein from 0.05 to 0.5 volume percentof a gasoline-soluble inert carrier oil is incorporated into saidcomposition.
 16. A fuel composition comprising a distillate fuelcontaining from 150 to 300 parts per million of a mixture of high andlow molecular weight hydrocarbyl amines having the general formula: 17.The gasoline composition defined in claim 16 wherein said high molecularweight amine is polyisobutenyl having an average molecular weight in thepolyisobutenyl portion of 2,500 to 4,400 ethylene diamine and said lowmolecular weight amine is polyisobutenyl ethylene diamine having anaverage molecular weight in the polyisobutenyl portion of 300 to 550.18. A gasoline composition defined in claim 16 wherein from 0.05 to 0.5volume percent of a gasoline-soluble inert carrier oil is incorporatedinto said composition.
 19. A gasoline composition containing a mixtureof high and low molecular weight hydrocarbyl mono- or polyamines; saidhigh molecular weight hydrocarbyl amine containing at least onehydrocarbyl group having a molecular weight from 1,900 to 5,000 and saidlow molecular weight hydrocarbyl amine containing at least onehydrocarbyl group having a molecular weight from 300 to 600; the weightratio of said low molecular weight hydrocarbyl amine to said highmolecular weight hydrocarbyl amine is between about 0.5 and 5:1.